gno.land/p/samcrew/urlfilter/v0⧉

1// Package urlfilter provides functionality to filter items based on URL query parameters.2// It is designed to work with an avl.Tree structure where each key represents a filter3// and each value is an avl.Tree containing items associated with that filter.4package urlfilter56import (7	"net/url"8	"strings"910	"gno.land/p/nt/bptree/v0"11	"gno.land/p/nt/ufmt/v0"12	"gno.land/p/sunspirit/md/v0"13)1415// ApplyFilters filters items based on the "filter" query parameter in the given URL16// and generates a Markdown representation of all available filters.17//18// Expected `items` structure:19//   - `items` is an *bptree.BPTree where each key is a filter name (e.g., "T1", "size:XL", "on_sale")20//     and each value is an *bptree.BPTree containing the items for that filter.21//   - Each item tree uses:22//     Key   (string): Unique item identifier23//     Value (any)   : Optional associated item data24//25// Example:26//27//	// Build the main filters tree28//	filters := bptree.NewBPTree32()29//30//	// Subtree for filter "T1"31//	t1Items := bptree.NewBPTree32()32//	t1Items.Set("item1", nil)33//	t1Items.Set("item2", nil)34//	filters.Set("T1", t1Items)35//36//	// URL with active filter "T1"37//	u, _ := url.Parse("/shop?filter=T1")38//39//	mdFilters, items := ApplyFilters(u, filters, "filter")40//41//	// mdFilters	→ Markdown links for toggling filters42//	// items    	→ AVL tree containing the filtered items43func ApplyFilters(u *url.URL, items *bptree.BPTree, paramName string) (string, *bptree.BPTree) {44	active := parseFilterMap(u.Query(), paramName)45	allFilters := make([]string, 0)46	resultTree := bptree.NewBPTree32()4748	// Iterate over each filter group in the items tree49	items.Iterate("", "", func(filterKey string, subtree interface{}) bool {50		allFilters = append(allFilters, filterKey)5152		tree, ok := subtree.(*bptree.BPTree)53		if !ok {54			return false55		}5657		// Add items to result if there are no active filters58		// or if the current filter is active59		tree.Iterate("", "", func(itemKey string, _ interface{}) bool {60			if len(active) == 0 || active[filterKey] {61				resultTree.Set(itemKey, filterKey)62			}63			return false64		})65		return false66	})6768	// Build Markdown links for toggling each filter69	var sb strings.Builder70	for _, f := range allFilters {71		q := toggleFilterQuery(active, f, allFilters, paramName)72		urlStr := buildURL(u.Path, q)73		sb.WriteString(ufmt.Sprintf(" | %v ", md.Link(formatLabel(f, active[f]), urlStr)))74	}7576	return sb.String(), resultTree77}7879// buildURL returns a path + query string, omitting the "?" if no query exists.80func buildURL(path string, query url.Values) string {81	if enc := query.Encode(); enc != "" {82		return path + "?" + enc83	}84	return path85}8687// parseFilterMap reads the "filter" query parameter and converts it into a map88// where keys are filter names and values are true for active filters.89//90// Example:91//92//	"filter=T1,T2" -> map[string]bool{"T1": true, "T2": true}93func parseFilterMap(query url.Values, paramName string) map[string]bool {94	filterStr := strings.TrimSpace(query.Get(paramName))95	if filterStr == "" {96		return map[string]bool{}97	}98	m := make(map[string]bool)99	for _, f := range strings.Split(filterStr, ",") {100		if f = strings.TrimSpace(f); f != "" {101			m[f] = true102		}103	}104	return m105}106107// toggleFilterQuery returns a new query string with the given filter toggled.108// - If the filter is currently active, it will be removed.109// - If it is inactive, it will be added.110// The order of filters follows the `all` list for consistency.111func toggleFilterQuery(active map[string]bool, toggled string, all []string, paramName string) url.Values {112	newFilters := []string{}113	for _, f := range all {114		if f == toggled {115			if !active[f] { // Add if it was inactive116				newFilters = append(newFilters, f)117			}118		} else if active[f] { // Keep other active filters119			newFilters = append(newFilters, f)120		}121	}122	q := url.Values{}123	if len(newFilters) > 0 {124		q.Set(paramName, strings.Join(newFilters, ","))125	}126	return q127}128129// formatLabel returns the Markdown-formatted label for a filter,130// showing active filters in bold (**filter**) and inactive filters131// with strikethrough (~~filter~~).132func formatLabel(name string, active bool) string {133	if active {134		return md.Bold(name)135	}136	return md.Strikethrough(name)137}138